Yellow Jacket Sling Psychrometer User manual

Brand: Yellow Jacket

Model: Sling Psychrometer

Type: User manual

This streamlined, compact sling psychrometer measures the wet and dry bulb temperatures of the surround-

ing air and permits immediate conversion of the readings to relative humidity percentage on the "slide rule"

scale which is an integral part of the case.

The "slide rule" indications are accurate to 1% of "Hygrometric Tables". For greater precision, use Bulletin

WB 235, available from Supt. of Documents, U. S. Government Printing Office, Washington, D. C. Relative

humidity is a ratio of the amount of water vapor in a given volume of air to the amount that would be present

if the air were saturated. A sling psychrometer operates on the principle of the evaporation of water from the

wet bulb thermometer and the resulting cooling effect on this thermometer.

How to use the 69010 Sling Psychrometer:

1. Pull shaft (A) from the case to the locked position.

2. Remove the thermometer slide (B) from the case and fill the reservoir (C) with clean water saturating

the full wick. Close the reservoir cover and snap the slide hook over the extended shaft.

3. Hold the case (as shown) and whirl the thermometer as rapidly as possible (at least two revolutions per

second) to effect evaporation around the wet bulb reducing the temperature to its lowest point. A sub-

stantial air velocity at the bulbs is necessary to obtain maximum accuracy.

4. When no further reduction in the wet bulb temperature is noted, read first the wet bulb and then the dry

bulb temperatures. A minute or more may be needed. The time necessary to bring the wet bulb tem-

perature to its lowest point will vary depending upon the temperature of the water in the reservoir: for

minimum delay the water should be at ambient temperature.

5. To read the relative humidity, insert the thermometer slide into the case, scale side up. Set the arrow on

the slide at the dry bulb temperature. The relative humidity is then read at the intersection of the RH

scale and the wet bulb temperature.

How to maintain your Sling Psychrometer:

1. Keep the slide and shaft fully closed when not in use.

2. Do not expose the instrument to direct sunlight or excessive heat for a prolonged period or damage

may result.

3. For best results the wick should be kept clean. When the wick around the bulb becomes dirty, cut this

section off and attach a new section from the excess wick in the reservoir. Additional wicks, Part

69011, may be ordered. To replace the wick start it through the opening from outside with a pointed

object.

4. Thermometers may be replaced by removing the clamp screws. Avoid over-tightening the screws when

setting the clamp.

5. Do not twist the slide or thermometer breakage is possible.

6. During shipment, the liquid may become separated in the bore or a bubble may form in the bulb. To

reunite column, remove the thermometer from the plastic slide and immerse the bulb only in a mixture

of ice, salt and water or dry ice and alcohol for greater cooling. After liquid has receded into bulb,

remove and hold the thermometers in vertical position until liquid has expanded gradually into lower

part of bore. If separation persists, repeat procedure.

Sling

Psychrometer

Ritchie Engineering Co., Inc.

YELLOW JACKET Products Division

10950 Hampshire Ave., S.

Bloomington, MN 55438-2623 USA

e-mail: [email protected]

Web Site: www.yellowjacket.com

Phone: 800-769-8370

Int’l Phone: 952-943-1333

Fax: 800-322-8684

Int’l Fax: 952-943-1605

UPC No. Description

69010 Sling Psychrometer

69011 Replacement wicks (5 pack)

69015 Replacement thermometer